Amount Of CO2 Research Articles

Molecular simulation of the effect of water content on CO2, CH4, and N2 adsorption characteristics of coal

The objective of this work was to investigate the sorption behavior of gases, namely CO2, CH4, and N2, by molecules of coal sampled from Linglu mine under different water inclusion rates. To this end, the adsorption, diffusion, adsorption heat, and potential energy distribution characteristics of the gases in the coal pores at different water inclusion rates were analyzed using molecular dynamics and grand canonical ensemble Monte Carlo methods. The results showed that the adsorption relationship of the coal molecules on CO2, CH4, and N2 exhibited a downtrend followed by an uptrend when the water content was increased from 0 to 3.6%. The adsorption amount of CO2 was approximately twice as much as those of CH4 and N2, indicating that the competitive adsorption advantage of CO2 compared with those of CH4 and N2 was unaffected by the water content. The trend in the average heat of adsorption was generally consistent with the trend in the density of coal molecules under different moisture contents. Under the same conditions, the diffusion coefficient within a coal molecule was negatively related to the water content in the system. The layer spacing of the water molecules (2.875 Å) was greater than the liquid–water layer spacing, indicating the formation of a water molecule layer at this point, which inhibited gas adsorption. This study lays a theoretical foundation for further investigating the microscopic mechanism of coal–water interaction.

Enhanced Fire Safety of Energy-Saving Foam by Self-Cleavage CO2 Pre-Combustion and Phosphorus Release Post-Combustion

Rigid polyurethane foam (RPUF) is widely utilized in construction and rail transportation due to its lightweight properties and low thermal conductivity, contributing to energy conservation and emission reduction. However, the inherent flammability of RPUF presents significant challenges. Delaying the time to ignition and preventing flame spread post-combustion is crucial for ensuring sufficient evacuation time in the event of a fire. Based on this principle, this study explores the efficacy of using potassium salts as a catalyst to promote the self-cleavage of RPUF, generating substantial amounts of CO2, thereby reducing the local oxygen concentration and delaying ignition. Additionally, the inclusion of a reactive flame retardant (DFD) facilitates the release of phosphorus-oxygen free radicals during combustion, disrupting the combustion chain reaction and thus mitigating flame propagation. Moreover, potassium salt-induced catalytic carbonization and phosphorus derivative cross-linking enhance the condensed phase flame retardancy. Consequently, the combined application of potassium salts and DFD increases the limiting oxygen index (LOI) and reduces both peak heat release rate (PHRR) and total heat release (THR). Importantly, the incorporation of these additives does not compromise the compressive strength or thermal insulation performance of RPUF. This integrated approach offers a new and effective strategy for the development of flame retardant RPUF.

Carbon Capture and Storage Subsurface Study for a Natural Gas-Burning Power Plant in Oltenia, Romania

The article presents carbon capture and storage, CCS, as a climate change mitigation method. Many industrial processes, such as the manufacture of cement, the metallurgical industry, and the production of electricity from fossil fuels, produce large CO2 quantities. Carbon capture and storage is a method for these industrial areas to become carbon neutral for the environment. To combat climate change, the EU wants to achieve climate neutrality by 2050, and this goal, along with an intermediate goal of reducing emissions by 55% by 2030, is enshrined in the European Climate Law. The EU has launched various initiatives to achieve these goals, one of which is the ‘Fit for 55’ legislation. The first step that countries wanting to apply these technologies must take is the evaluation of the underground CO2 storage potential. The potential for CO2 storage in the depleted hydrocarbon reservoirs in Oltenia, one of the eight regions of Romania, makes it possible to develop safe long-term storage projects for the neighboring power plants currently producing energy from burning coal or hydrocarbons. The results of dynamic simulations of CO2 storage in one of these geological structures, Bradesti, which hosts depleted hydrocarbon reservoirs, using a numerical simulator are successfully presented for the neighboring Isalnita Power Plant. In this case, the impact on the environment and climate will be minimal and in alignment with the European Union’s long-term objectives. Our study also opens the path for future similar analyses.

Flux-cored arc welding of 316L austenitic stainless steel: the effect of different shielding gas mixtures on microstructural features and weld performance

ABSTRACT Double-pass flux cored arc welding (FCAW) of 316 L austenitic stainless steel was performed using different shielding gas mixtures. Microstructural features and weld performance were evaluated. Based on the Creq/Nieq ratio of fusion zone and cooling rate, different morphologies of ferrite (skeletal, lathy, and dendritic) and austenite with various volume fractions were produced. An increase in Creq/Nieq ratio can increase the strength level because the presence of ferrite in the weld metal acts as a second-phase strengthening agent. On the other hand, ferrite is a suitable place for sigma phase precipitation. Highest joint efficiency resulted in the specimen welded via GTAW. The ductility of welds was ranked as CO2 +Ar shielded FCAW > GTAW > CO2 shielded FCAW > self-shielded FCAW. At room temperature, variation of delta-ferrite content (Creq/Nieq ratio) does not affect toughness. However, an increased amount of CO2 in shielding gas will result in decreased toughness values because of the enhanced formation of oxide inclusions. Increasing CO2 content of shielding gas from 0% to 18% and finally to 100% will result in decreasing toughness values from the highest value of 76J to 40 J and finally the lowest value of 38J.

Níveis de CO2, quebra técnica e qualidade dos grãos de milho armazenados em diferentes condições

ABSTRACT The use of CO2 sensors has been reported as an effective tool in the early detection of signs of deterioration, allowing good accuracy in decision-making about the quality of stored grains. The objective of this study was to quantify the CO2 levels produced by maize grains stored at ambient temperature in a prototype silo, with initial moisture contents of 14, 16 and 18% w.b., and to evaluate the quality of the product over time and the technical breakage. Analyses of moisture content, ash, proteins, lipids, Hue Angle (color), germination and electrical conductivity were performed. Inside the silos, the amount of CO2, relative air humidity and temperature were monitored every hour. Grain quality evaluations were carried out at four storage times (0, 30, 60 and 90 days). A completely randomized design in a 3 × 4 factorial scheme with six replicates was used. Grains with higher moisture contents showed higher technical breakage and losses associated with CO2 emissions. Moisture content, protein, lipids, germination, bulk density, lightness and chroma decreased over time, while the electrical conductivity increased, resulting in greater damage to membranes and loss of quality of maize grains. Monitoring of CO2 in the grain mass is a good tool to assess the quality of grain, and higher initial moisture content caused greater level of CO2 emission and reduction in quality of maize grains.

Deep-root respiration: The unknown CO2 removed from the atmosphere

Carbon (C) sequestration in soils is a promising CO2 removal approach. So far, the focus has been on how to increase the content of soil organic C (SOC), while the management soil inorganic C (SIC), i.e. carbonate minerals, has received little attention, because SIC is thought to be much less involved in biotic C cycling than SOC. However, in principle SIC management potentially provides a long-term solution, with a much greater capacity for C sequestration than SOC. The forgotten link is the dissolved inorganic carbon (DIC), i.e. CO2 species dissolved in soil solution, and its fate throughout the unsaturated zone (USZ). The return of CO2 respired by deep roots to the atmosphere, either directly through CO2 degassing or indirectly through DIC leaching, may not necessarily take place over decades or centuries. CO2 diffusion decreases sharply with depth due to reduced porosity of the subsoil and more water-filled pores. The downward water percolation rate is often only a few centimeters per year, and the large amount of respired CO2 compared to the leached DIC results in a relatively small amount of CO2 being transferred to the groundwater. Therefore, respired CO2 at deeper soil depth can be defined as a hitherto unknown ecosystem service of deep-rooted plants i.e. providing a net C sink as inorganic C in the USZ. A conservative estimation suggests a C sink as SIC of at least 80 kg C ha−1 y−1, comparable to reported annual C sequestration as SOC in temperate grasslands.

Investigation of carbon dioxide absorption performance in amine amino acid salts for upgrading biogas applications: Blended absorbents of piperazine and amino acid solutions

BackgroundThe increasing amount of CO2 in the atmosphere is a critical environmental issue, necessitating the development of efficient CO2 capture technologies. Amine amino acid solutions (AAAS) have demonstrated potential in improving CO2 absorption and desorption. This study explores the efficiency of various AAAS, including piperazine (PZ), glycine (Gly), lysine (Lys), sarcosine (Sar), and alanine (Ala), under specific experimental conditions. MethodologyThe CO2 absorption and desorption processes were investigated using AAAS under conditions of 45 % CO2 at 313.15 K and with pure N2 at 353.15 K, respectively. The findings obtained for CO2 loading, regeneration rate, CO2 desorption heat, and 13C nuclear magnetic resonance (NMR) are valuable for understanding their impacts on the design and improvement of energy efficiency CO2 capture techniques. Furthermore, the physicochemical properties of PZ + lysine solutions such as density, viscosity, and vapor pressure were also measured at equimolar concentration ranges such as 0.75 M, 1.0 M, 1.25 M, and 1.5 M at T = 303.15 K to 353.15 K and 0.1 MPa pressure. Significant findingsThe study revealed significant enhancements in CO2 absorption and desorption with the addition of AAAS compared to monoethanolamine (MEA) solutions. Notably, among all the solutions, the PZ + lysine solution exhibited the maximum CO2 cyclic capacity at 0.792 mol CO2/mol absorbent, and the lowest regeneration heat. These findings provide valuable insights into the design and improvement of energy-efficient CO2 capture techniques.

Carbon Sequestration in Agricultural Soil: Technique and their Efficiency

Developing technologies to slow the rate of increase in the atmospheric concentration of carbon dioxide (CO2) from annual emissions, such as energy, process industries, land-use change, and soil cultivation, is a major challenge of the twenty-first century. Severe ecological and economic disruptions result from the erratic changes in climate systems caused by the skyrocketing amounts of atmospheric CO2 and other greenhouse gases (GHGs). Through the process of carbon sequestration, net greenhouse gas emissions can be reduced, hence mitigating climate change. Both biotic and abiotic variables can contribute to the long-term sequestration of carbon, or carbon stabilisation. The compilation of past and present methods for sequestering soil organic carbon is crucial, considering the need of measuring and tracking soil carbon at the point, field, regional, and ecosystem levels. This study attempts to provide an overview of the literature about the function of various agricultural management techniques for sequestering carbon and the ways in which they help to stabilize atmospheric carbon.

Metal-organic frameworks (MOFs) for photoreduction of CO2

In recent decades, human industrialisation has become increasingly advanced, and the quality of life has also improved. Subsequently, the excessive consumption of fossil fuels has caused a series of problems, for example, global environmental warming caused by excessive CO2 emissions. Among numerous CO2 reduction technologies, using solar energy as an energy source for the CO2 photoreduction is considered one of the most prospective technologies. This method not only reduces the amount of CO2, but also enables to converse CO2 into other valuable chemicals, thereby achieving carbon cycling. Metal-organic frameworks (MOFs) are composed of metal ions and organic ligands as three-dimensional porous materials. MOFs have many advantages, including sizeable specific surface area, excellent CO2 absorption capacity and modifiable pore structure, leading to broad application potential in photocatalytic reduction of CO2. This article mainly introduces three aspects: functionalisation and modification of pure MOFs, MOF-based composite materials, and MOF-derived materials, which further improve the CO2 photocatalytic efficiency of MOFs. Furthermore, it includes the analysis of reported examples, discussion and outlook on reaction mechanisms and challenges. At present, the main difficulties faced by MOFs-based photocatalysts lie in their economic feasibility and poor material stability. Therefore, this review aims to help stimulate in-depth research in this area as well as better exert the advantages of MOFs.

Numerical Simulation Study of Combustion under Different Excess Air Factors in a Flow Pulverized Coal Burner

The basic national condition that is dominated by coal will not alter in the foreseeable future. Coal-fired boiler is the main equipment for coal utilization, and cyclone burner is a practical type of burner. There is a cyclone formation, a primary air duct inside the center air duct, and a secondary air duct. Introducing a small stream of pulverized coal gas or oil mist stream or gas directly into the reflux zone in the center duct ignites first a stable combustion and a small fluctuation of ignition pressure. In this paper, the variation of furnace temperature for cyclone pulverized coal burner corresponding to different excess air factors and the composition of gases such as O2, CO, CO2, and NOX produced by combustion were investigated using fluent software. A single cyclone pulverized coal burner from an actual coal-fired boiler is used, and a combustion zone applicable to the study of a single pulverized coal burner is established to study the actual operation of a single pulverized coal burner at different excess air coefficients. The findings indicate that the ignition position of pulverized coal combustion advances with decreasing α (Excess Air Factors); however, the length of the produced high-temperature flame gets shorter. As the value of α decreases, the burnout in the furnace decreases and the CO emission concentration increases, with a maximum CO mole fraction of 0.38% at α = 1.2 and a maximum CO mole fraction of 3.13% at the axial position when α decreases to 0.8. The furnace’s concentration of NOX, the NOX emission level decreases significantly with decreasing α. The NOX mole mass increases gradually with increasing α, and in the bottom portion of the primary combustion zone, more NOX is produced. The concentration of NOX in the chamber changes significantly after α exceeds 1.0, and the NOX at the outlet surges from 417.25 ppm to 801.07 ppm, which is attributed to the increase in the average temperature of the chamber, which promotes the generation of thermophilic NOX. The distribution pattern of O2 mole fraction along the furnace height cross-section at different excess air factors is basically the same, with a maximum at the burner inlet and a gradual decrease in the O2 content as it enters the combustion chamber to react with the pulverized coal in a combustion reaction. The value of α = 0.8 when the air supply is obviously insufficient, the fuel cannot be fully combusted, and only a small amount of CO2 is produced.

Representing Carbon Dioxide Transport and Storage Network Investments within Power System Planning Models

Carbon dioxide (CO2) capture and storage (CCS) is frequently identified as a potential component to achieving a decarbonized power system at least cost; however, power system models frequently lack detailed representation of CO2 transportation, injection, and storage (CTS) infrastructure. In this paper, we present a novel approach to explicitly represent CO2 storage potential and CTS infrastructure costs and constraints within a continental-scale power system capacity expansion model. In addition, we evaluate the sensitivity of the results to assumptions about the future costs and performance of CTS components and carbon capture technologies. We find that the quantity of CO2 captured within the power sector is relatively insensitive to the range of CTS costs explored, suggesting that the cost of CO2 capture retrofits is a more important driver of CCS implementation than the costs of transportation and storage. Finally, we demonstrate that storage and injection costs account for the predominant share of total costs associated with CTS investment and operation, suggesting that pipeline infrastructure costs have limited influence on the competitiveness of CCS.

Effect of methane addition on supercritical water oxidation of poultry manure in the flow mode

The paper presents the research results of the supercritical water oxidation (SCWO) of poultry manure continuously fed into a tubular reactor both in the absence and presence of methane as an auxiliary fuel. The tests were conducted at a temperature gradient along the vertical axis of the reactor (top to bottom: 390–600 °C), a pressure of 25 MPa, and varying reagent flow rates. It is shown that due to heat generation during methane oxidation the energy consumption from external sources is reduced by 1.3–1.5 times depending on the ratio of reagent flow rates. The gas products contain CO2, N2, and trace amounts of N2O. The ash residues are predominantly composed of calcite and hydroxyapatite. The addition of methane results in a reduction in the content of phenols and polycyclic aromatic hydrocarbons present in the aqueous effluent, while content of N-bearing aromatics increases. The formation of nitrophenols was observed at elevated oxygen concentrations in the reaction mixture. It was revealed that excess oxygen plays a pivotal role in the efficacy of organic nitrogen removal. The formation of mineral acids and a high level of ammonia in the reaction mixture during the SCWO of poultry manure result in corrosion of stainless steel and copper seals, which in turn leads to an increased concentration of chromium and copper in the aqueous effluent. The results obtained indicate the potential for utilizing natural gas in an environmentally friendly and resource-saving manner for poultry manure processing by SCWO in autothermal mode.

A Comparison Between Water Addition and CO2 Addition to a Diffusion Coflow Flame

ABSTRACT This work compares the effects of adding water vapor and CO2 as diluent to fuel for a diffusion flame at different ambient pressures. The approach of this research is to study numerically a methane diffusion flame with various amounts of water vapor and CO2 added to the fuel, and to compare the flame behaviors with various percentages of water vapor and CO2 content (0% to 65%). This work uses a coflow burner in the PeleLM numerical framework for simulating the flame and computing the combustion behavior. The flame was simulated with pressures of 1.0, 1.4, 5.7, and 11.1 atm. The results extracted and analyzed include temperature profiles at fixed heights and various species mole fractions compared with their values at an equilibrium state condition. The results show that most of the diluent impact does not involve changes in flame chemistry but primarily changes to heat release and heat capacity in the flames. The results also show that the diluent amount has a much larger impact on flame behavior than do changes in pressure.

Petrocella pelovolcani sp. nov., an Alkaliphilic Anaerobic Bacterium Isolated from Terrestrial Mud Volcano

Diversity of extremophilic microorganisms in mud volcanoes is largely unexplored. Here we report the isolation of a novel alkaliphilic, mesophilic, fermentative bacterium (strain FN5sucT) from a terrestrial mud volcano located at the Taman Peninsula, Russia. Cells of strain FN5sucT are gram-stain-positive, non-sporeforming, motile rods. The temperature range for growth is 10–37°C, with an optimum at 30°C. The pH range for growth is 7.5–10.0, with an optimum at pH 9.0. The isolate utilizes various organic polymeric substances, organic acids, carbohydrates, and proteinaceous compounds. The end products of carbohydrates fermentation are acetate, CO2 and trace amounts of H2 and formate. The major cellular fatty acid compounds are C16:0, C16:1 ω7c, and monounsaturated dimethyl acetal C14:1. Phylogenetic analysis reveals that strain FN5sucT is most closely related to Petrocella atlantisensis = DSM 105309T (98.4% 16S rRNA gene identity). The total size of the genome of strain FN5sucT is 3.35 Mb, and a genomic DNA G+C content is 37.0 mol %. The genome contains complete glycolisis/glyconeogenesis pathway. We propose to assign strain FN5sucT to the genus Petrocella, as a new species, Petrocella pelovolcani sp. nov. The type strain is FN5sucT (=DSM 113898T = UQM 41591T).

Ultrasensitive optical fiber SPR sensor enhanced by Au-NPs-film modified with functionalized CQDs for label-free detecting cobalt (II) ion

BackgroundCobalt, an essential trace element, is vital for maintaining human nervous system function, aiding in DNA synthesis, and contributing to red blood cell production. It is helpful for disease diagnosis and treatment plan evaluation by precisely monitoring its concentration changes in the human body. Despite extensive efforts made, due to its ultra-low concentration, the current limit of detection (LOD) as reported is still inadequate and cannot be satisfied with the precise clinical applications. Therefore, it is crucial to develop novel label-free sensors with high sensitivity and excellent selectivity for detecting trace amounts of Co2+. ResultsHere, an ultrasensitive optical fiber SPR sensor was designed and fabricated for label-free detection of Co2+ with ultra-low concentration. It is achieved by modifying the carboxyl-functionalized CQDs on the AuNPs/Au film-coated hetero-core fiber, which can specifically capture the Co2+, leading to changes in the fiber's surface refractive index (RI) and subsequent SPR wavelength shifts in the transmission spectrum. Both the Au film and AuNPs on the fiber are modified with CQDs, leveraging their large surface area to enhance the number of active sites and probes. The sensor exhibits an ultra-high sensitivity of approximately 6.67 × 1019 nm/M, and the LOD is obtained as low as 5.36 × 10−20 M which is several orders of magnitude lower compared to other conventional methods. It is also experimentally demonstrated that the sensor possesses excellent specificity, stability, and repeatability, which may be adapted for detecting real clinical samples. SignificanceThe CQDs-functionalized optical fiber SPR sensor exhibits substantial potential for precisely detecting Co2+ of trace amounts, which is especially vital for scarce clinical samples. Additionally, the sensing platform with sample sensor fabrication and measurement configuration introduces a novel, highly sensitive approach to biochemical analysis, particularly adapting for applications involving the detection of trace targets, which could also be employed to detect various biochemical targets by facile modification of CQDs with specific groups or biomolecules.

Transport Instabilities of Hazardous Contaminants in a Microscale Soil Sample Under Thermal Flow of Supercritical CO2

This work reveals the transient dynamics of supercritical carbon dioxide (sCO2) under a joint heat and mass interactions with resident polycyclic aromatic hydrocarbons (PAHs) in sedimentary microporous media. A variant of Multiphase Color Fluid Lattice Boltzmann model is developed to simulate spatiotemporal evolution of sCO2 front with degradation of a 5 μm mass-film of resident PAHs. The injection conditions of sCO2 range from 305 K to 315 K, and from 8 MPa to 10 MPa, with a mass flow rate of 0.05–0.15 kg/min. It has been found in this study that the growth of clusters reveals a critical operating time to promote the solvation power of sCO2. However, the cluster of such contaminants is affected by a secondary degradation inside the pore throats of the microporous. The heat and mass coefficients are remarkably relied on the nature of the contaminants and their clustering/clogging processes inside the pores. Hence, the saturation amount of CO2 will jump from a prompt movement to a quick equilibrium state while facing the balanced phase of clustering/degradation of resident contaminants inside the microporous media.

A Comprehensive Review on Carbon Sequestration Potential and Addition of Organic Carbon to Soil

Various soil management techniques can be used to sequester carbon in agricultural fields. With widespread implementation, these methods could sequester a substantial amount of carbon. For the purpose of removing carbon from the atmosphere and storing it in the soil, various management techniques exist. The efficacy of these tactics varies depending on the region, soil type, and climate. The longevity of soil sequestration and the ideal circumstances for maximising the reduction of carbon emissions remain topics of discussion. This essay examines the process by which soil stores carbon, the current status of soil carbon research, and the controversy surrounding the potential of soil carbon. It emphasises the numerous side advantages of raising soil carbon and provides a set of suggestions for further investigation. A substantial amount of soil organic carbon (SOC) might be sequestered by switching from conventional to conservation tillage, although this change would only have a long-term impact on tillage practices. Crop rotation based on legumes is more effective than that based on grass in converting biomass carbon to soil organic carbon. Rotational grazing lowers the overall quantity of CO2 released into the atmosphere while improving the quality of the grass. Producing biochar and incorporating it into soil is an additional strategy for storing carbon from the atmosphere.

Synergy of alloy and ligand for CO2 hydrogenation to formic acid on PdAu/HPC-AP

Formic acid (FA) is of great significance given its extensive applications in various industrial fields. At present, methanol carbonylation is the main industrial production process of FA. However, this process uses two kinds of raw materials from fossil fuels and emits a large amount of CO2. Alternatively, converting CO2 into FA can not only achieve the production of value-added chemicals but also effectively address environmental issues caused by CO2 emission. To improve the low reactivity of CO2, homogeneous and heterogeneous catalytic systems have been widely evaluated, among which heterogeneous catalytic systems are attracting ever-increasing attention owing to their great industrialization prospects. However, some of these heterogeneous catalysts suffer from low catalytic performance. Herein, PdAu alloy nanoparticles anchored on amine-functionalized hierarchical porous carbon (PdAu/HPC-AP) were constructed to drive efficient converting of CO2 into FA. Characterization and testing results demonstrated that the introduced Au atoms caused lattice distortion and charge redistribution on the surface of the bimetallic catalyst, facilitating the adsorption and activation of reaction molecules. Furthermore, the modification of HPC with an appropriate amount of amine ligands was found important to the chemical adsorption of CO2 and the dispersion of PdAu NPs. The Pd60Au40/HPC-AP catalyst with the optimum synergy of alloy and ligand demonstrated excellent activity for the target reaction with a TOF value of 486 h–1 at 100 °C. Moreover, it can even catalyze the reaction at room temperature with a TOF value of 13 h–1.

Techno-economic assessment of supercritical, cold liquid, and dissolved CO2 injection into sub-seafloor basalt

Injecting CO2 into subsea basalt can provide permanent storage via multiple trapping mechanisms, including mineralization reactions which convert the CO2 into solid carbonates over time. Injecting CO2 together with water can accelerate the process of mineralization, but presents additional challenges, such as high energy and water requirements. A techno-economic model of CO2 transport and injection into ocean basalt was developed to compare injection strategies using pure supercritical CO2, pure liquid CO2, and CO2 dissolved in seawater. The model was applied to a representative injection site off the coast of British Columbia, Canada. Injection of CO2 dissolved into seawater was found to be more energy and cost intensive than injection of supercritical or liquid CO2; this is primarily due to the reduced quantities of CO2 that can be injected into each well, and additional pumping energy required for the accompanying seawater. For the base assumptions, transport and storage costs for supercritical, liquid, and dissolved injection were estimated as $43/t, $38/t, and $250/t respectively. Their energy requirements were estimated as 93 kWh/t, 90 kWh/t, and 213 kWh/t respectively. The current best estimates of geological parameters for ocean basalt suggest good injectivity and very large storage capacities per well. This may help to compensate for the additional project expenses incurred by deep water, allowing cost-effective liquid and supercritical injection. However, this result is sensitive to high uncertainties in both geological parameters and component cost data.

Experimental study on CO2 sequestration capacity and mechanical characteristics evolution of solid wastes based carbon-negative backfill materials

The employment of solid waste, notably coal gangue, in carbon-negative backfill mining technology for mineralization and filling in coal mine gobs, is recognized as a productive method for carbon sequestration and waste management, with research primarily dedicated to engineering advanced mineralized backfill materials. Under this background, four variables, including the ratio of gangue to solids (RG-S), water-cement ratio (RW-C), ratio of fly ash to solid wastes providing calcium (Ca) (RA-Ca), and ratio of flue gas desulfurization (FGD) gypsum to carbide slag (RF-CS) were defined to formulate gangue-based mineralized backfill materials, with orthogonal experiments assessing their effects on CO2 sequestration and mechanical characteristics. The results indicate that RW-C consistently emerges as the primary factor influencing both the amount of sequestered CO2 and the mechanical properties of gangue-based solid waste mineralized backfill materials. The amount of sequestered CO2 demonstrates a direct proportionality to RW-C and mechanical strength demonstrates an inverse relationship with RW-C. After 45 minutes of stirring and carbon sequestration, samples in various groups exhibited an maximum sequestered CO2 amount of 18.96 g·kg−1, with a maximum sequestration rate of 0.20 g·kg−1·min−1. The process of CO2 sequestration enhances the compressive properties of mineralized backfill materials derived from gangue based solid wastes.